This invention relates generally to networking, and in particular, to a power indicating Ethernet outlet and method therefor.
Local area networks (LANs) have grown tremendously in the last few years. And, leading the way in the growth of LANs is the Ethernet type LAN. Ethernet was first developed in the mid 1970s. By the early 1980s, the Institute of Electrical and Electronic Engineers (IEEE) developed a standard for Ethernet designated as IEEE 802.3, which has been universally adopted by the network industry. From the early 1980s until the present, the IEEE 802.3 standard has undergone many revisions, including the addition of new features such as switched Ethernet, Fast Ethernet, Gigabit Ethernet, and others. The present invention relates to a proposed new addition to the IEEE 802.3 standard project (P802.3af) of transmitting power over Ethernet transmission lines, as explained below.
FIG. 1 illustrates a current exemplary Ethernet network system 100 as may be employed in an office environment, home, or other establishment. The network system 100 typically comprises at least one network core device 128, such as a hub, router, bridge, repeater, etc., and at least one network device 102, such as a network telephone, clock, light switch, desktop computer, laptop computer, personal digital assistants, and other devices that can interface with a network system. The network core device 128 and the network device 102 are data coupled together via a data transmission line 120, such as those specified by IEEE 802.3 (e.g. 10BASE-T, 10BASE-F, 100BASE-TX etc.).
The network core device 128 may comprise network interfaces 130, data processing circuits 134, and memory 136 all data coupled together for performing the designated functions of the network core device. The network core device 128 may also include a power supply 132 for supplying direct current (DC) power to the each of the elements of the network core device 128, such as the network interfaces 130, the data processing circuits 134, and the memory 136. The power supply 132 may, in turn, receive alternating current (AC) power from a standard AC outlet 126 mounted on a wall 122 or, alternatively from an Uninterruptible Power Supply (UPS). The network interfaces 130 may be coupled to one or more cable transmission lines which are connected to work area telecommunications outlets 124 mounted on the wall 122 for communicating with one or more network devices, such as network device 102 by way of data transmission line 120. A specification for cabling infrastructure, cable transmission lines and work area telecommunications outlets is called out at reference ISO/IEC 11801.
The network device 102 may also comprise a network interface 108, data processing circuit 104, and memory 106 all data coupled together for performing its various functions. The network device 102 may also include a power supply 110 for supplying direct current (DC) power to the each of the elements of the network device 102, such as the network interface 108, the data processing circuit 104, and the memory 106. The power supply 110 may, in turn, receive alternating current (AC) power from a standard AC outlet 118 mounted on a wall 112, or alternatively some other sources of uninterruptible power. The network interface 108 may be coupled to a cable transmission line connected to a work area telecommunications outlet 114 mounted on the wall 112 for communicating with one or more network core devices, such as network core device 128 by way of data transmission line 120.
One drawback of the current Ethernet network system 100 is that typically each device requires its own power supply for supplying power to its various functional elements. Thus, there is a lot of redundancy in the current Ethernet network system 100. Furthermore, each network device requires two sets of cabling for operation. For instance, network device 102 has a cabling for connecting to the work area telecommunications outlet 114 and another cabling for connection to the AC outlet 118. Noting the redundancy and the cabling drawbacks of the current Ethernet network system 100, the IEEE is proposing an addition to the. IEEE 802.3 standard to allow transmission of power by way of the specified Ethernet cabling from a network core device to one or more network devices. This would eliminate the requirement of a power supply for each network device and also reduce cabling since each network device need only connect to a work area telecommunications outlet, and not additionally to an AC outlet.
FIG. 2 illustrates an exemplary Ethernet network system 200 that may incorporate the transfer of power across Ethernet cabling as being proposed by the IEEE. The network system 200 comprises at least one network core device 228 having a network interface 230, a data processing circuit 234, memory 236, and a power supply 232 coupled to an AC outlet 226 mounted on wall 222. The network interface 230, in turn, comprises a data interface and a power insertion circuit. The network interface 230 is coupled to one or more cables connected to a work area telecommunications outlet 224 mounted on wall 222. Similarly, the network device 202 comprises a network interface 208, data processing circuit 204, memory 206, and a DC-to-DC converter 210. The network interface 208, in turn, comprises a data interface and a power removal circuit. The network interface 208 of the network device 202 is coupled to a cable for connecting to work area telecommunications outlet 214 mounted on wall 212. In this case, however, the network system 200 includes a cabling 220 for communicating not only data, but also power for supplying power from the network core device 228 to one or more network devices 202.
More specifically, the power generated by the power supply 232 is sent to the power insertion circuit of the network interface 230 for transmission to the network device 202 by way of the cabling 220. The power removal circuit of the network interface 208 of the network device 202 receives this power from the telecommunications outlet 214, and sends it to the DC-to-DC converter 210 for generating the appropriate power level for each of its elements. In this way, the network device 202 need not have its own AC-powered internal power supply, but merely draws the power coming from the work area telecommunication outlet 214. It is proposed that the power may be transmitted on an unused twisted pair of wires which are available in some of the IEEE 802.3 compliant cabling, or with the addition of a phantom circuit to the two twisted pairs of wires currently in some IEEE 802.3 compliant cabling.
It is also proposed that the power on the transmission line 220 remains off when the network device 202 is not connected to the work area transmission outlet 214. Instead, the network core device 228 generates and transmits a load verification signal through the transmission line 220 when there is no qualified network device connected to the work area telecommunications outlet 214. The network core device 228 uses the load verification signal to determine whether there is a qualified network device connected to the work area telecommunications outlet 214, and possibly the type of network device connected for the purpose of transmitting the appropriate power level to the network device. It is proposed that this load verification signal is a relatively low power and low duty cycle pulsed signal. Once the network core device 228 senses a qualified network device connected to the outlet 214, it ceases transmitting the load verification signal, and transmits instead the power level required by the network device.
With this new proposed addition to the IEEE 802.3 standard, a user will need to know whether a particular work area telecommunications outlet is capable of supplying power. Such a need is met with the apparatus and method of the invention.
A telecommunications outlet is provided with a visual indicator which informs a user that the outlet is capable of supplying power to a network device. The telecommunications outlet is capable of supplying power to a network device when it receives a load verification signal received from a network core device. A network core device transmits the load verification signal to the telecommunications outlet to determine whether there is a qualified network device connected to the outlet, and possibly the type of network device connected for the purpose of transmitting the appropriate power level to the network device. When the load verification signal is not present at the telecommunications outlet, the outlet is not capable of supplying power to a network device.
The telecommunications outlet of the invention comprises a visual indicator and a visual indicator driver circuit. The driver circuit generates a driving signal in response to the load verification signal. Thus, when the load verification signal is present, the driver circuit generates the driving signal which causes the visual indicator to activate, thereby visually informing any users of the outlet""s capability of supplying power.
The load verification signal may comprise a train of low power and low duty cycle pulses. To generate a driving signal in response to the pulsing load verification signal, the visual indicator driver circuit comprises a charge accumulating circuit to form a ramping voltage by accumulating charges each time it receives a pulse of the load verification signal, and an oscillator to generate a driving pulse when the pump voltage is greater than a threshold. The driving pulse causes the visual indicator to activate. The visual indicator need not xe2x80x9cblinkxe2x80x9d at the same frequency of the pulsing load verification signal, but may blink once for every several pulses received. Accordingly, the oscillator threshold may be set to provide a visual blinking of the visual indicator which is comfortable to view.
Other aspects, features, and techniques of the invention will become apparent to those skilled in the relevant art in view of the following detail discussion of the invention.